AIR POLLUTION EFFECTS ON AGRICULTURAL CROPS IN ONTARIO: A REVIEW

Abstract

Photochemical oxidants, sulphur dioxide and fluoride are the major air pollutants affecting agricultural crops in Ontario, but scientific documentation of their effects is limited, particularly for sulphur dioxide and fluoride. Airborne road salt, cement dust, soot, boron, nickel, cobalt and ammonia have also been implicated in a few localized instances of crop injury. The most widespread injury to agricultural crops is caused by photochemical oxidants, mainly in southern Ontario where tobacco, bean, potato, grape, cucumber, onion, tomato and other crops have been affected. Sulphur dioxide has had significant effects on forests and natural vegetation in Ontario, and may become important in agricultural areas due to the proliferation of coal-fired electric generating stations. The effects of sulphur dioxide in combination with other gaseous pollutants such as photochemical oxidants, and the long-term effects of acid precipitation are current concerns. In addition, there have been a few cases of fluoride injury to crops localized around fluoride-emitting industries. Very few estimates of economic losses to agricultural crops have been documented anywhere and to date no assessment of the economic value of air pollution damage to agricultural crops in Ontario has been attempted.